External quality assessment of point-of-care International Normalized Ratio (INR) testing in Europe

Abstract

Background: Point-of-care testing (POCT) of prothrombin time, expressed as International Normalized Ratio (INR), is widely used to monitor patients in oral anticoagulation treatment. Guidelines recommend that POCT users should participate in an external quality assessment (EQA) scheme whenever available. The aim of this study was to investigate which European countries provide EQA for POCT INR and to compare how these schemes are organized. Methods: Thirty European countries were invited to participate in this study. Those who reported that they provide EQA for POCT INR filled in a questionnaire dealing with different aspects of their schemes. Results: Nineteen countries reported that they do not provide EQA for POCT INR, while 12 organizations from nine countries reported that they provide this service. Most of these countries circulate lyophilized samples with for the participants unknown target values. Samples with certified INR values and procedures using split samples with fresh patient samples are also used. The acceptability limits vary from 15% to 30%, and the total number of samples circulated per year varies from 1 to 12. Most of the countries organize educational activities together with their schemes. Conclusions: This study demonstrates that there is a wide variation in the way EQA for POCT INR is performed in Europe and that there are many European countries that do not provide this service. Even though our findings indicate that EQA for POCT INR draws some challenges, especially in providing suitable control materials, participation in such schemes is considered useful.

External Quality Assessment of Point-of-Care Methods: Model For Combined Assessment of Method Bias and Single-Participant Performance by the Use of Native Patient Samples and Noncommutable Control Materials

“…The Danish quality specification for a method bias of 6% (23 ) was used. The quality specification for a deviating result from method target was set to 15%, which is the most commonly used quality specification for EQA for POC INR in Europe (14 ). One of the likely reasons why this quality specification is wider than the specification for method bias is that it includes random error as well as the systematic error.…”

“…However, a recent study (14 ) has shown that in most European countries EQA for POC INR testing is not provided, primarily because of the lack of a suitable control material. The study also showed that different types of EQA schemes are provided and all have advantages and limitations.…”

“…The study also showed that different types of EQA schemes are provided and all have advantages and limitations. The main drawback of the most common schemes is that they use noncommutable control samples (lyophilized materials), and alternative approaches have therefore been developed (14 ).…”

Analytical performance specifications for external quality assessment – definitions and descriptions

“…Different EQA providers however use a wide range of APS for the same measurand [2][3][4][5]. A survey performed by the European Organisation for External Quality Assurance Providers in Laboratory Medicine (EQALM) in 2014 showed that the criteria used to set the APS also vary widely [6], which is presumably a strong contributor to the variation in APS.…”

Preparation of Control Blood for External Quality Assessment of Point-of-Care International Normalized Ratio Testing in the Netherlands

“…1 Patients who have monitored their therapy at home with a point-of-care INR monitor have demonstrated an ability to achieve a high rate of time in a therapeutic range, as documented in clinical trials. 2 Guidelines recommend that POCT users (eg, anticoagulation clinics) should participate in an external quality assessment scheme (EQAS).…”